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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Vasilyeva I. G., Dovlitova L. S., Zaikovskii V. I., Malakhov V. V., Edel'man I. S., Stepanov A. S., Aleksandrov K. S.
Заглавие : Actual composition and structure of manganese ferrite nanoparticles dispersed in the borate glass matrix
Место публикации : Doklady Chemistry. - 2005. - Vol. 401, Is. 1-3. - P.47-50. - ISSN 0012-5008, DOI 10.1007/s10631-005-0029-y
Ключевые слова (''Своб.индексиров.''): boric acid--ferrite--glass--manganese derivative--analytic method--article--chemical composition--chemical structure--nanoparticle--stoichiometry--structure analysis--transmission electron microscopy--x ray analysis
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Belskaya N. A., Moshkina E. M., Bezmaternykh L. N., Vasiliev A. D., Sofronova S. N., Eremina R. M., Eremin E. V., Muftakhutdinov A. R., Cherosov M. A., Ovchinnikov S. G.
Заглавие : Antiferromagnetism of the cation-ordered warwickite system Mn2-xMgxBO4 (x=0.5, 0.6 and 0.7)
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [20-02-00559]; Government of Krasnoyarsk Territory; Krasnoyarsk Regional Fund of Science to the research project [18-42243007]
Место публикации : J. Magn. Magn. Mater. - 2020. - Vol. 507. - Ст.166820. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2020.166820. - ISSN 1873-4766(eISSN)
Примечания : Cited References: 39. - The reported study was funded by the Russian Foundation for Basic Research (no. 20-02-00559), Government of Krasnoyarsk Territory, Krasnoyarsk Regional Fund of Science to the research project. 18-42243007.
Предметные рубрики: SPIN-GLASS BEHAVIOR
CRYSTAL-STRUCTURES
SINGLE-CRYSTALS
INSIGHTS
MGFEBO4
Аннотация: X-ray diffraction, heat capacity and magnetic measurements are performed on single crystals of Mn2-xMgxBO4 (x = 0.5, 0.6 and 0.7) with the warwickite structure. The monoclinic symmetry is found for all samples with the space group P21/n. The M1 site is occupied by trivalent Mn ions while the M2 site is occupied by a mixture of divalent Mg and Mn ions. Regular cation and charge distributions are observed, which is unusual for heterometallic warwickites. The local octahedral distortions of M1O6 show the monotonic dependence on the Mg content and are in accordance with the Jahn-Teller distortion. All samples are found to undergo long-range antiferromagnetic ordering with rather low transition temperatures of TN = 16, 14 and 13 K for x = 0.5, 0.6, and 0.7, respectively. The ordering of local octahedral distortions, caused by the strong electron-phonon interaction of the trivalent Mn ions, is proposed to stabilise the cationic ordering and, as a result, the long-range magnetic ordering in the material.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Khodenkov S. A., Yushkov I. A.
Заглавие : Band-pass filters based on photonic crystal
Коллективы : International School and Conference on Optoelectronics, Photonics, Engineering and Nanostructures, Saint Petersburg OPEN, International School and Conference on Optoelectronics, Photonics, Engineering and Nanostructures
Место публикации : J. Phys. Conf. Ser. - 2017. - Vol. 917, Is. 6. - Ст.062043. - ISSN 17426588 (ISSN), DOI 10.1088/1742-6596/917/6/062043
Примечания : Cited References: 5. - This study was supported by the Ministry of Education and Science of the Russian Federation, grant МК-9119.2016.8.
Ключевые слова (''Своб.индексиров.''): amplitude frequency characteristics--connection coefficients--glass substrates--high contrast--high frequency hf--periodic interchange--relative bandwidth--ultra-wideband filters
Аннотация: Multilayer photonic crystal structures with bleaching layers are being investigated. In order to calculate the characteristics of ultra-wideband filters on their basis, T-lines lossless model was used. Amplitude-frequency characteristics for the synthesized filters of 5th, 11th and 17th orders are given. It is proved that by a significant increase in filter N order, the difference between the connection coefficients of central resonators' layers' becomes negligible. This makes it possible to develop 27-order filter, in which almost half of the layers are realized by periodic interchange of only two identical high-contrast materials. The investigated band-pass filters, including the ones on a glass substrate, have high frequency-selective properties at a relative bandwidth of 80%.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Anshits A. G., Bayukov O. A., Kondratenko E. V., Anshits N. N., Pletnev O. N., Rabchevskii E. V., Solovyov L. A.
Заглавие : Catalytic properties and nature of active centers of ferrospheres in oxidative coupling of methane
Коллективы : Russian Science Foundation [14-13-00289]
Место публикации : Appl. Catal. A-Gen.: Elsevier Science, 2016. - Vol. 524. - P.192-199. - ISSN 0926-860X, DOI 10.1016/j.apcata.2016.06.032. - ISSN 1873-3875(eISSN)
Примечания : Cited References:47. - This study was supported by the Russian Science Foundation (project no. 14-13-00289).
Предметные рубрики: GLASS CRYSTAL CATALYSTS
MAGNETIC-PROPERTIES
PROFILE REFINEMENT
FLY-ASH
MOSSBAUER
MICROSPHERES
PERFORMANCE
CONVERSION
ETHYLENE
OXIDE
Ключевые слова (''Своб.индексиров.''): methane coupling--active center--ferrospinel--mossbauer spectroscopy
Аннотация: Ferrospheres with the Fe2O3 content in the range from 76 to 97 wt% were applied as catalysts for the oxidative coupling of methane (OCM). To identify their phase composition and distribution of iron sites, the ferrospheres were characterized by X-ray powder diffraction and Mossbauer spectroscopy before and after the OCM reaction. Magnetite-based ferrite spinel, hematite and aluminosilicate glasses were established to be the main phases. The ferrospinel of all ferrospheres partially oxidized to hematite after the OCM reaction. It was established that the yield of C-2-hydrocarbons sharply increased at the ferrospheres with Fe2O3 content higher than 89 wt% The spinel phase of these ferrospheres includes Fevv3+(B) sites with a Ca2+ tetrahedral cation and an octahedral cation vacancy among the nearest neighbors. A linear correlation between the yield of C-2-hydrocarbons (ethane and ethylene) and the content of such sites was established, thus indicating that their electrophilic oxygen species participate in selective CH4 conversion to C2H6. (C) 2016 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shapovalov V. V., Shapovalov V. A., Sluzhbin Yu. A., Drokina T. V., Vorotynov A. M., Valkov V. I.
Заглавие : Characteristics of nanocomplexes with iron Fe3+ in Glass Ionomer Cement powder by ESR method
Место публикации : Phys. Solid State. - 2023. - Vol. 65, Is. 2. - P.296-298. - ISSN 10637834 (ISSN), DOI 10.21883/PSS.2023.02.55415.489. - ISSN 10906460 (eISSN)
Примечания : Cited References: 13
Аннотация: The study is part of nanomedical biotechnology and is carried out by probing these systems using the Electronic Spin Resonance (ESR) method. The paper investigates Glass Ionomer Cement powder widely used in dental practice Glass Ionomer Cement C-Plus Triplekit-TM. To assess the quality of Glass Ionomer Cement and use ESR radiospectroscopy in the range from low (T=4.2 K) to room (T=300 K) temperatures. A new characteristic of compounds with nanocomplexes of magnetic iron ions Fe3+ is applied.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fomenko E. V., Akimochkina G. V., Knyazev Yu. V., Semenov S. V., Yumashev V. V., Solovyov L. A., Anshits A. G.
Заглавие : Characterization and magnetic properties of sintered glass-ceramics from dispersed fly ash microspheres
Место публикации : Magnetochemistry. - 2023. - Vol. 9, Is. 7. - Ст.177. - ISSN 23127481 (eISSN), DOI 10.3390/magnetochemistry9070177
Примечания : Cited References: 50. - Russian Science Foundation and the Krasnoyarsk Regional Science Foundation, grant number 22-27-20039, https://rscf.ru/project/22-27-20039/ (accessed on 15 March 2023)
Аннотация: The recycling of hazardous industrial waste into high-tech materials with desired properties is of considerable interest since it provides optimal alternatives for its final disposal. Coal fly ash, the major waste generated by coal-fired power plants, contains significant quantities of dispersed microspheres with a diameter smaller than 10 μm, which are anthropogenic atmospheric pollutants PM10. Due to their composition and fine-grained powder morphology, they can be converted into sintered products. In this study, dispersed microspheres from class C fly ash were directly sintered without any additive to form high-strength glass-ceramics with magnetic properties. The optimum processing conditions were achieved at a temperature of 1200 °C, at which samples with a compressive strength of 100.6 MPa were obtained. Sintering reduces the quantity of the glass phase and promotes the formation of larnite, Fe-spinel, ye’elimite, and ternesite. Mössbauer measurements show that the relative concentration of the magnetic phase compared to the paramagnetic one rises almost in order. The sintered sample demonstrates a narrower distribution of the hyperfine magnetic field and a significantly lower value of the coercive field of 25 Oe, which allows proposing such materials as soft magnetic materials. The presented results demonstrate promising industrial applications of hazardous PM10 to minimize solid waste pollution.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Stolyar S. V., Yaroslavtsev R. N., Ladygina V. P., Balaev D. A., Pankrats A. I., Iskhakov R. S.
Заглавие : Collective Spin Glass State in Nanoscale Particles of Ferrihydrite
Коллективы : International Symposium “Nanostructures: Physics and Technology”
Место публикации : Semiconductors. - 2020. - Vol. 54, Is. 12. - P.1710-1712. - DOI 10.1134/S1063782620120362
Примечания : Cited References: 16. - This work was supported by the Russian Foundation for Basic Research, the Government of the Krasnoyarsk Territory, the Krasnoyarsk Regional Fund for the Support of Scientific and Technical Activities (project no. 19-42-240012 r_a “Magnetic resonance in ferrihydrite nanoparticles: Effects associated with the “core–shell” structure). This work was supported by a grant from the President of the Russian Federation for state support of young Russian scientists – candidates of sciences no. MK-1263.2020.3
Аннотация: Ferromagnetic resonance was used to study three types of ferrihydrite nanoparticles: nanoparticles formed as a result of the cultivation of microorganisms Klebsiella oxytoca; chemically prepared ferrihydrite nanoparticles; chemically prepared ferrihydrite nanoparticles doped with Cu. It is established from the ferromagnetic resonance data that the frequency-field dependence (in the temperature range ТP ‹ T ‹ T*) is described by the expression: 2πν/γ ⁼ НR + HA(T = 0)(1 – T/Т*), where γ is the gyromagnetic ratio, HR is the resonance field. The induced anisotropy HA is due to the spin-glass state of the near-surface regions. TP temperature characterizes the energy of the interparticle interaction of nanoparticles.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Moshkina E. M., Eremin E. V., Veligzhanin, Alexey, Pavlovskiy M. S., Sofronova S. N., Titova, Veronika, Bezmaternykh L. N.
Заглавие : Concentration transition in Cu2(Mn,Ga)BO5 solid solutions
Колич.характеристики :13 с
Место публикации : J. Magn. Magn. Mater. - 2023. - Vol. 584. - Ст.171072. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2023.171072. - ISSN 18734766 (eISSN)
Примечания : Cited References: 27
Аннотация: The effects related to the conversion of magnetic structures of a Cu2MnBO5 ferrimagnet to a Cu2GaBO5 antiferromagnet under the Mn3+ → Ga3+ substitution were studied. The properties of four single crystal samples with the gallium concentration x = 0.04, 0.11, 0.17, 0.25 were examined. The chemical composition and valence state of the samples were determined by X-ray absorption spectroscopy element-sensitive technique. Distribution of the 3d metal ions over crystallographic positions was studied using the first principle calculations by Wien2k program. The evolution of the magnetic properties was investigated by the measurements of the temperature and field dependences of magnetization, dc and ac magnetic susceptibility. In agreement with the previous study of the structure evolution of Cu2Mn1-xGaxBO5 solid solutions, the critical concentration upon a change in the magnetic ordering type was found in the range x = 0.17–0.25. The non-monotonic behavior of magnetization in terms of the gallium content was found in the concentration range of 0.04–0.17. A complex pattern of magnetic phase transitions belonging to the concentration phase boundary was obtained in the compounds with gallium being within the range x = 0.17–0.25. One could observe the splitting of the peaks of the real part of ac-susceptibility of the high-temperature phase transition in the Cu2MnBO5-like phase (x = 0.04, 0.11) and that of the low-temperature one at the concentration boundary (x = 0.17, 0.25) with different frequency and orientational dependence. The type and origin of the multiple phase transitions observed in the studied samples were analyzed.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Platunov M. S., Knyazev Yu. V., Ivanova N. B., Zubavichus Y. V., Veligzhanin A. A., Vasiliev A. D., Bezmaternykh L. N., Bayukov O. A., Arauzo A., Bartolome J., Lamonova K. V., Ovchinnikov S. G.
Заглавие : Crystal and local atomic structure of MgFeBO4,Mg0.5Co0.5FeBO4, and CoFeBO4: effects of Co substitution
Место публикации : Phys. Status Solidi B. - 2015. - Vol. 252, Is. 10. - P.2245-2258. - ISSN 0370, DOI 10.1002/pssb.201552143. - ISSN 15213951 (eISSN)
Примечания : Cited References: 46. - This work has been financed by the MECOM Project MAT11/23791, and DGA IMANA project E-34, Council for Grants of the President of the Russian Federation (project nos. NSh-2886.2014.2, SP-938.2015.5), and Russian Foundation for Basic Research (project nos. 13-02-00958-a, 13-02-00358-a, 14-02-31051-mol-a). The work of one of the coauthors (M.S.P.) was supported by the program of Foundation for promoting the development of small enterprises in scientific and technical sphere ("UMNIK" program).
Предметные рубрики: SPIN-GLASS BEHAVIOR
MAGNETIC WARWICKITES
SINGLE-CRYSTALS
PHASE-RELATIONS
OXYBORATE
SYSTEM
SPECTROSCOPY
ANISOTROPY
MN2OBO3
FE2OBO3
Ключевые слова (''Своб.индексиров.''): crystal structure--xanes--exafs--magnetic semiconductor--oxyborate
Аннотация: Single-crystalline MgFeBO4, Mg0.5Co0.5FeBO4, and CoFeBO4 have been grown by the ﬂux method. The samples have been characterized by X-ray spectral analysis, X-ray diffraction, and X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) and extended X-ray absorption ﬁne structure (EXAFS) spectra have been measured at the Fe and Co K-edges over a wide temperature range (6.5– 300 K). The composition, the charge state, and local environ- ment of both Fe and Co atoms have been determined. The effects of Co substitution for Mg on the local structural distortions have been revealed experimentally and the M–O bond anisotropy has been found.Монокристаллические образцы CoFeBO4 были выращены раствор-расплавным методом. Образцы были охарактеризованы с помощью рентгеноспектрального анализа, рентгеновской дифракции и спектроскопии поглощения рентгеновских лучей. Спектры вблизи K-края поглощения рентгеновского излучения структуры (XANES) и далее рентгеновского поглощения тонкой структуры (EXAFS) были измерены для Fe и Co в широком диапазоне температур (6.5- 300К). Состав, состояние заряда, и локальная положение и Fe и Co атомов были определены. Эффекты замещения Co магнием Mg на местные структурные искажения были выявлены экспериментально и анизотропия связи М-О была найдена.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Moshkina E. M., Nazarenko I. I., Seryotkin Yu. V., Nepijko S. A., Ksenofontov V., Medjanik K., Veligzhanin A. A., Bezmaternykh L. N.
Заглавие : Crystal growth, structure, magnetic properties and theoretical exchange interaction calculations of Cu2MnBO5
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 420. - P.309-316. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2016.07.019
Примечания : Cited References: 35. - X-ray diffraction experiment was carried out at the Centre on Molecular Design and Ecologically Safe Technologies at the Novosibirsk State University. The reported study was funded by Russian Foundation for Basic Research (RFBR) and Government of Krasnoyarsk Territory according to the research project No. 16-42-243028.
Предметные рубрики: SPIN-GLASS BEHAVIOR
SINGLE-CRYSTALS
SUPEREXCHANGE INTERACTIONS
LUDWIGITE
DIELECTRICS
CO3B2O6NI3B2O6
WARWICKITES
FE3O2BO3
IFEFFIT
NI3B2O6
Ключевые слова (''Своб.индексиров.''): oxyborates--ludwigites--xmcd--exafs--magnetism
Аннотация: Single crystals of ludwigite Cu2MnBO5 were synthesized by flux growth technique. The detailed structural and magnetic characterizations of the synthesized samples have been carried out. The cations composition of the studied crystal was determined using X-ray diffraction and EXAFS technique, the resulting composition differ from the content of the initial Mn2O3–CuO components of the flux. Magnetic susceptibility measurements and the calculations of the exchange integrals in frameworks of indirect coupling model revealed that monoclinic distortions strongly affect exchange interactions and appearance of magnetic ordering phase at the temperature T=93 K. The hypothesis of the existence of several magnetic subsystems was supposed. © 2016 Elsevier B.V.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu.V., Ivanova N. B., Kazak N. V., Platunov M. S., Bezmaternykh L. N., Velikanov D. A., Vasiliev A. D., Ovchinnikov S. G., Yurkin G. Yu.
Заглавие : Crystal structure and magnetic properties of Mn substituted ludwigite Co3O2BO3
Место публикации : J. Magn. Magn. Mater.: Elsevier Science BV, 2012. - Vol. 324, Is. 6. - P.923-927. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2011.07.044
Примечания : Cited References: 15. - The study was supported by the Russian Foundation for Basic Research (Project no. 09-02-00171-a), the Federal Agency for Science and Innovation (Rosnauka) (Project no. MK-5632.2010.2), the Physical Division of the Russian Academy of Science, the program "Strongly Correlated Electrons", Project 2.3.1.
Предметные рубрики: BOND VALENT SUMS
COORDINATION CHEMISTRY
OXIDATION -STATE
O BONDS
COMPLEXES
MANGANESE
COBALT
Ключевые слова (''Своб.индексиров.''): transition metal oxyborate--distinct crystallographic position--spin glass magnetic ordering
Аннотация: The needle shape single crystals Co3−x MnxO2BO3 with ludwigite structure have been prepared. According to the X-ray diffraction data the preferable character of distinct crystallographic positions occupation by Mn ions is established. Magnetization field and temperature dependencies are measured. Paramagnetic Curie temperature value Θ=−100 K points out the predominance of antiferromagnetic interactions. Spin-glass magnetic ordering takes the onset at TN=41 K. The crystallographic and magnetic properties of Co3O2BO3:Mn are compared with the same for the isostructural analogs Co3O2BO3 and CoO2BO3:Fe.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Xia Y., Chen J., Liu Y.-G., Molokeev M. S., Guan M., Huang Z., Fang M.
Заглавие : Crystal structure evolution and luminescence properties of color tunable solid solution phosphors Ca2+xLa8-x(SiO4)6-x(PO4)xO2:Eu2+
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2016. - Vol. 45, Is. 3. - P.1007-1015. - ISSN 14779226 (ISSN), DOI 10.1039/c5dt03786g
Примечания : Cited References: 42. - This work was sponsored by National Natural Science Foundation of China (Grant No. 51472223), the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-12-0951) and the Fundamental Research Funds for the Central Universities (Grant No. 2652015020).
Предметные рубрики: LIGHT-EMITTING-DIODES
WHITE-LIGHT
ENERGY-TRANSFER
SILICATE GLASS
SINGLE-PHASE
EU2+
LEDS
PHOTOLUMINESCENCE
EMISSION
UV
Аннотация: A series of apatite solid solution phosphors Ca2+xLa8-x(SiO4)6-x(PO4)xO2:Eu2+ (x = 0,2,4,6) were synthesized by a conventional higherature solid-state reaction. The phase purity was examined using XRD, XPS and XRF. The crystal structure information, such as the concentration, cell parameters and occupation rate, was analyzed using a Rietveld refinement, demonstrating that the Eu2+ activated the Ca2La8(SiO4)6O2 and Ca8La2(PO4)6O2 to form continuous solid solution phosphors. Different behaviors of luminescence evolution in response to structural variation were verified among the series of phosphors. Two kinds of Eu2+ ion sites were proved using low temperature PL spectra (8k) and room temperature decay curves. The substitution of large La3+ ions by small Ca2+ ions induced a decreased crystal field splitting of the Eu2+ ions, which caused an increase in emission energy from the 5d excited state to the 4f ground state and a resultant blue-shift from 508 nm to 460 nm. Therefore, with the crystal structure evolution, the emitted color of the series of phosphors could be tuned from green to blue by adjusting the ratio of Ca/La. © 2016 The Royal Society of Chemistry.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kulbakov A. A., Sarkar R., Janson O., Dengre S., Weinhold T., Moshkina E. M., Portnichenko P. Y., Luetkens H., Yokaichiya F., Sukhanov A. S., Eremina R. M., Schlender P., Schneidewind A., Klauss H. -H., Inosov D. S.
Заглавие : Destruction of long-range magnetic order in an external magnetic field and the associated spin dynamics in Cu2GaBO5 and Cu2AlBO5 ludwigites
Место публикации : Phys. Rev. B. - 2021. - Vol. 103, Is. 2. - Ст.024447. - ISSN 24699950 (ISSN), DOI 10.1103/PhysRevB.103.024447
Примечания : Cited References: 46. - We thank U. Nitzsche for technical assistance. This project was funded in part by the German Research Foundation (DFG) under Grant IN 209/9-1, via Project C03 of the Collaborative Research Center SFB 1143 (project-id 247310070) at the TU Dresden, and the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter—ct.qmat (EXC 2147, project-id 390858490). O.J. was supported by the Leibniz Association through the Leibniz Competition
Аннотация: The quantum spin systems Cu2M′BO5 (M′=Al,Ga) with the ludwigite crystal structure consist of a structurally ordered Cu2+ sublattice in the form of three-leg ladders, interpenetrated by a structurally disordered sublattice with a statistically random site occupation by magnetic Cu2+ and nonmagnetic Ga3+ or Al3+ ions. A microscopic analysis based on density-functional-theory calculations for Cu2GaBO5 reveals a frustrated quasi-two-dimensional spin model featuring five inequivalent antiferromagnetic exchanges. A broad low-temperature 11B nuclear magnetic resonance points to a considerable spin disorder in the system. In zero magnetic field, antiferromagnetic order sets in below TN≈4.1 K and ∼2.4 K for the Ga and Al compounds, respectively. From neutron diffraction, we find that the magnetic propagation vector in Cu2GaBO5 is commensurate and lies on the Brillouin-zone boundary in the (H0L) plane, qm=(0.45,0,−0.7), corresponding to a complex noncollinear long-range ordered structure with a large magnetic unit cell. Muon spin relaxation is monotonic, consisting of a fast static component typical for complex noncollinear spin systems and a slow dynamic component originating from the relaxation on low-energy spin fluctuations. Gapless spin dynamics in the form of a diffuse quasielastic peak is also evidenced by inelastic neutron scattering. Most remarkably, application of a magnetic field above 1 T destroys the static long-range order, which is manifested in the gradual broadening of the magnetic Bragg peaks. We argue that such a crossover from a magnetically long-range ordered state to a spin-glass regime may result from orphan spins on the structurally disordered magnetic sublattice, which are polarized in magnetic field and thus act as a tuning knob for field-controlled magnetic disorder.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Drokin N. A., Kumakhov M. A., Shabanov V. F.
Заглавие : Dielectric properties of liquid crystals in polycapillary matrices
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 6. - P1315-1322. - ISSN 1063-7834, DOI 10.1134/S1063783410060314
Примечания : Cited References: 24. - This study was supported by the Council on Grants from the President of the Russian Federation (grant no. 3818.2008.3) and the Siberian Branch of the Russian Academy of Sciences (Integration Project no. 5) and performed within the framework of the State Contract (no. 02.740.11.0220).
Предметные рубрики: MOLECULAR-SIEVES
SILICA AEROGEL
POROUS-GLASS
MEMBRANES
NMR
8CB
Аннотация: This paper reports on the results of investigations into the dielectric properties of liquid crystals embedded in polycapillary matrices and describes a technique for their measurement. It has been revealed that the chemical structure of the rigid core and the length of mobile alkyl groups of liquid-crystal molecules of the alkylcyanobiphenyl group substantially affect the equilibrium configuration of the liquid-crystal director in capillaries. The reorientation of liquid-crystal molecules embedded in capillaries in the nematic phase under the influence of an external magnetic field has been investigated.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Udod L. V., Sitnikov M. N., Kretinin V. V., Molokeev M. S., Mironova-Ulmane N.
Заглавие : Dipole glass in chromium-substituted bismuth pyrostannate
Коллективы : Russian Foundation for Basic Research [N 18-52-00009 Bel_a, 18-32-00079 mol_a, 3.5743.2017/6.7]
Место публикации : Mater. Res. Express. - 2018. - Vol. 5, Is. 11. - Ст.115202. - ISSN 2053-1591, DOI 10.1088/2053-1591/aaddd9
Примечания : Cited References: 33. - This study was supported by the Russian Foundation for Basic Research project N 18-52-00009 Bel_a, No 18-32-00079 mol_a, the state order No 3.5743.2017/6.7.
Предметные рубрики: BI4TI3O12 THIN-FILMS
NEUTRON-DIFFRACTION
RAMAN-SPECTROSCOPY
BI2SN2O7
Ключевые слова (''Своб.индексиров.''): dipole glass--permittivity--polarization--raman scattering spectra--structural transition
Аннотация: To establish the existence of dipole glass in the chromium-substituted bismuth pyrostannate solid solutions, the frequency and temperature dependences of the permittivity have been measured in the temperature range of 300–750 K. The field and dynamic dependences of polarization in the temperature range of 80–550 K have been determined. Using the Raman scattering spectra, the absence of inversion center has been established. The maximum of electrical resistance has been found in the vicinity of the dipole moment freezing point. The carrier type has been determined from the thermopower data. The polarization relaxation is shown to be nonexponential. The experimental data are explained within the model of dipole glass in the α- phase and the model of charged crystalline domain walls with the electron-polarization relaxation mechanism above the α–β structural transition.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Semenov S. V., Balaev A. D., Balaev D. A.
Заглавие : Dissipation in granular high-temperature superconductors: New approach to describing the magnetoresistance hysteresis and the resistive transition in external magnetic fields
Коллективы : Russian Science Foundation [17-72-10050]
Место публикации : J. Appl. Phys. - 2019. - Vol. 125, Is. 3. - Ст.033903. - ISSN 0021-8979, DOI 10.1063/1.5066602. - ISSN 1089-7550(eISSN)
Примечания : Cited References: 79. - The work was supported by the Russian Science Foundation (Grant No. 17-72-10050). We are grateful to K. Terent'ev for the preparation of the sample and D. Gokhfeld for useful discussions.
Предметные рубрики: CRITICAL-CURRENT-DENSITY
VORTEX-GLASS SUPERCONDUCTIVITY
ANISOTROPIC ENERGY-DISSIPATION
Аннотация: An approach to describing the R(H) magnetoresistance hysteresis in granular high-temperature superconductors and behavior of the R(T) resistive transition in these objects in an external magnetic field is proposed. The dissipation is attributed to the subsystem of intergrain boundaries, which form a Josephson junction network. The approach is based on accounting for the effect of magnetic moments of superconducting grains on the resulting (effective) field in the intergrain medium. The described procedure includes (i) establishing of the degree of magnetic flux crowding in the intergrain medium by comparing the experimental data on the R(H) magnetoresistance hysteresis and magnetization M(H), (ii) determining the effective field Beff in the intergrain medium as a function of external field H and temperature T with regard to the thermomagnetic prehistory, and (iii) fitting the experimental R(H) and R(T) dependences using the Arrhenius expression R ∼ exp(–EJ/ kB T), where EJ is the parameter corresponding to the Josephson coupling energy. The fundamental novelty of the proposed approach is the extraction of the functional dependences of EJ on the effective field Beff in the intergrain medium rather than on the external field H, as was made in many previous works. It is shown that the proposed approach makes it possible to adequately describe both the R(H) hysteretic dependences and R(T) dependences of the Y-Ba-Cu-O high-temperature superconductor samples with different morphologies and critical current densities.
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17.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Shapovalov V. V., Shapovalov V. A., Sluzhbin Yu. A., Drokina T. V., Vorotynov A. M., Shavrov V. G., Valkov V. I.
Заглавие : Dynamic characteristics of a nanocomplex with iron in glass-ionomer cement powder
Коллективы : Российская академия наук, Физико-технический институт им. Е.К. Завойского ФИЦ Казанского научного центра РАН, Казанский (Приволжский) федеральный университет, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : VIII Euro-Asian symposium "Trends in magnetism" (EASTMAG-2022): Book of abstracts/ program com. S. G. Ovchinnikov [et al.]. - 2022. - Vol. 1, Sect.: Spin dynamics and magnetic resonances. - Ст.B.O15. - P.258-260. - ISBN 978-5-94469-051-7
Примечания : Cited References: 6
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhaleva E. A., Flerov I. N., Kartashev A. V., Gorev M. V., Bogdanov E. V., Bondarev V. S., Korotkov L. N., Rysiakiewicz-Pasek E.
Заглавие : Effect of a restricted geometry on thermal and dielectric properties of NH4HSO4 ferroelectric
Коллективы : Russia/CIS/Baltic/Japan Symposium on Ferroelectricity , Russian Foundation for Basic Research (RFBR) [16-32-00092 mol_a]
Место публикации : Ferroelectrics. - 2017. - Vol. 513, Is. 1. - P.44-50. - ISSN 0015-0193, DOI 10.1080/00150193.2017.1350436. - ISSN 1563-5112(eISSN)
Примечания : Cited References:17. - The reported study was partially supported by the Russian Foundation for Basic Research (RFBR), research project No. 16-32-00092 mol_a.
Предметные рубрики: PHASE-TRANSITIONS
AMMONIUM
CAPACITY
SULFATE
KH2PO4
Ключевые слова (''Своб.индексиров.''): ferroelectric--phase transition--porous glass--nanocomposite
Аннотация: Heat capacity, thermal dilatation, sensitivity to pressure and permittivity of NH4HSO4 embedded into glass matrices with a pore size of 320 nm and 46 nm were studied. Large difference in the thermal expansion of both glass and ferroelectric leads to a "clamped" state of NH4HSO4 in nanocomposites and to the phase transition temperatures change. The restricted geometry does not effect on the order of successive transformations in NH4HSO4 but is accompanied by a significant reduction in entropy of phase transitions. The behavior of DTA-signal and permittivity show the expansion of the temperature range of the ferroelectric phase under hydrostatic pressure.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Arauzo A., Bartolome J., Luzon J., Drokina T. V., Petrakovskii G. A., Molokeev M. S.
Заглавие : Effect of R substitution in spin glass RFeTi2O7 compounds
Место публикации : J. Magn. Magn. Mater. - 2020. - Vol. 515. - Ст.167273. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2020.167273
Примечания : Cited References: 38. - This study has been financed by MECOM Project MAT2014-53921-R, MICINN Project MAT2017-83468-R and Gobierno de Aragón RASMIA E12_17R. Authors would like to acknowledge the use of Servicio General de Apoyo a la Investigación-SAI, Universidad de Zaragoza
Аннотация: Zirconolite oxides R3+Fe3+Ti2O7 (R rare earth element) are known to exhibit spin glass behaviour at low temperatures. Here we present a detailed study of these compounds for R = Eu, Gd, Dy, Ho, and Er, together with reviewed previous measurements on Sm, Tb, Tm, Yb and Lu, with the scope of determining the role played by the rare earth on their magnetic properties. They have been investigated using X-ray powder diffraction, and further characterized by magnetization, frequency dependent ac susceptibility and heat capacity measurements. RFeTi2O7 compounds are all isostructural showing orthorhombic structure, space group Pcnb at 300 K. Disorder of the magnetic ions in the RFeTi2O7 lattice induces spin glass behaviour at low temperatures, mainly due to the Fe sublattice. We show that magnetic rare earth ions participate in the spin glass state tuning its properties. The single ion anisotropy of the R3+ ions, excluding exchange interaction with other magnetic ions, has been calculated by ab initio methods, and expressed in terms of the g tensor of the ground doublet or quasi-doublet in Kramers (Sm, Dy, Er, Yb) and non-Kramers (Tb, Ho) ions, respectively, in an effective spin S* = 1/2 model. In the case of R with a singlet ground state (Eu, Tm) or a multiplet state (Gd), the ion is isotropic. We show that the relative increase in the spin-glass temperature ΔTSGR/TSGFe with respect to the LuFeTi2O7, where Lu is non-magnetic, correlates qualitatively with the product of the ratio gz/gJ (R = Tb, Dy, Ho, and Er), or g⊥/gJ (R = Sm), times the ratio of exchange interactions JR,Fe/JFe,Fe determined from the paramagnetic room temperature susceptibility measurements. Besides, for increasing anisotropy the spin glass transition dynamics slows down to values typical of cluster glass. The coercive field below the transition is increased in the same trend. This paper explains the effect of the R-Fe exchange interaction and R single ion anisotropy on the spin-glass behaviour of these compounds.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhaleva E. A., Flerov I. N., Kartashev A. V., Gorev M. V., Molokeev M. S., Bogdanov E. V., Bondarev V. S., Korotkov L. N., Rysiakiewicz-Pasek E.
Заглавие : Effect of restricted geometry and external pressure on the phase transitions in ammonium hydrogen sulfate confined in a nanoporous glass matrix
Место публикации : J. Mater. Sci. - 2018. - Vol. 53, Is. 15. - P.12132–12144. - ISSN 00222461 (ISSN), DOI 10.1007/s10853-018-2467-1
Примечания : Cited References: 44. - The reported study was funded by Russian Foundation for Basic Research (RFBR) according to the Research Project No. 16-32-00092 mol_a.
Ключевые слова (''Своб.индексиров.''): hydraulics--hydrostatic pressure--permittivity--pore size--specific heat--sulfur compounds--thermal expansion
Аннотация: A study of heat capacity, thermal dilatation, susceptibility to hydrostatic pressure, permittivity and polarization loops was carried out on NH4HSO4–porous glass nanocomposites (AHS + PG) as well as empty glass matrices. The formation of dendrite clusters of AHS with a size, dcryst, exceeding the pore size was found. An insignificant anisotropy of thermal expansion of AHS + PG showing statistically uniform distribution of AHS with random orientations of nanocrystallites over the matrix was observed. The effect of internal and external pressures on thermal properties and permittivity was studied. At the phase transition P-1 ↔ Pc, a strongly nonlinear decrease in the entropy ΔS2 and volume strain (ΔV/V)T2 was observed with decreasing dcryst. The linear change in temperatures of both phase transitions P-1 ↔ Pc ↔ P21/c under hydrostatic pressure is accompanied by the expansion of the temperature range of existence of the ferroelectric phase Pc, while this interval narrows as dcryst decreases.
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